Our climate is changing—with notable impacts on birds and biodiversity already recorded around the world. As the magnitude of these changes intensifies, there are likely to be profound alterations to the natural systems and biological communities on which we and future generations depend. Ever-increasing evidence suggests that healthy ecosystems will help us to adapt to and withstand the worst impacts of climate change. Protecting and expanding the existing network of Important Bird Areas will make a vital contribution to safeguarding both biodiversity and local communities during this period of climatic uncertainty.

The climate of our planet is changing as a result of escalating greenhouse gas emissions, caused by the burning of fossil fuels and the destruction of forests. Temperatures globally have increased causing the ice caps and arctic permafrost to melt, sea levels to rise and patterns of precipitation and snow cover to shift. The magnitude of these changes is predicted to intensify significantly over the coming century with far-reaching, and almost entirely detrimental, impacts on the Earth’s natural systems and biological communities anticipated ().

Already, there is strong evidence that climate change is influencing a wide range of organisms, with impacts documented for over 600 bird species (, ). These effects have included marked shifts in the timing of avian life cycle events, such as migration and breeding. Crucially, such changes are not always consistent across taxa. So, for example, many bird species that have evolved to synchronise the timing of their annual routines with the life cycles of other species are at risk of becoming ecologically mismatched and competitively disadvantaged. For example, whilst the brood-parasitic Common Cuckoo Cuculus canorus has advanced its migration only modestly, many of its host species are now arriving at the breeding grounds considerably earlier ().

Climate is a critical factor in determining species’ geographical distributions. Across Europe and North America, research is revealing a remarkably consistent pattern of northward range expansions (). These trends are mirrored in the southern hemisphere, with some Australian species moving south by as much as 200–300 km in just two decades (). Already climate change is having a damaging impact on avian communities. A Climatic Impact Index for Europe’s birds has revealed a clear response to climate change since the mid-1980s. Critically, it shows that three times more species have been negatively impacted by climate change than positively affected ().

Modelling studies indicate that the ranges currently occupied by many species may become unsuitable for them as climate change continues (, ). One study suggests that, by the end of this century, the breeding ranges of European birds will shift north-eastwards by several hundred kilometres. On average, future ranges are expected to be 20% smaller than they are now, with limited overlap (c.40%) with present distributions (). Species predicted to experience a substantial range loss and shift, such as Marmora’s Warbler Sylvia sarda, are of particular concern ().

Preliminary analysis suggests that a high percentage of the world’s bird species—including many not yet considered threatened—possess characteristics that render them vulnerable to climate change (). Seabirds are particularly susceptible (, ).

The polar regions are likely to undergo some of the most dramatic changes in climate. Species occurring in the high Arctic have limited opportunities for dispersing to new areas of suitable habitat and may be at particular risk (). Similarly vulnerable will be mountain-top species, which will find themselves increasingly trapped in ever-shrinking pockets of suitable climate space (). Sea level rise poses a major threat to coastal ecosystems and the biota they support (). The Endangered Bermuda Petrel Pterodroma cahow is already suffering from wave damage to nesting sites during increasingly frequent and severe hurricanes (). Climate change is also likely to exacerbate many existing threats such as invasive species. For example, in Hawaii, increased temperatures will further assist the spread of introduced mosquitoes, which have already decimated many endemic bird populations through the transmission of avian pox and malaria ().

Furthermore, inappropriate and ill-conceived mitigation measures also have detrimental impacts on biodiversity. For example, clearance of natural habitats to cultivate biofuels, as an alternative to fossil fuels, increasingly threatens birds and other biodiversity (, ). In particular, clearing forested land for biofuel crops is a seriously flawed premise that will accelerate, rather than arrest, climate change (). Whilst it is a clear imperative to find clean, sustainable alternatives to fossil fuels, it is critical that the implications of new technologies for wildlife are fully considered. Wind power has emerged as a leading renewable technology and is currently the fastest growing source of energy in the world. However, there are growing concerns that badly-sited turbines could pose a considerable collision risk to birds ().

Climate change will have profound implications for humankind. Already the impacts of drought, crop failure, flooding, sea-level rise, and extreme weather events are being felt across the world, with the poorest people and most vulnerable ecosystems hit hardest. Healthy, bio-diverse environments play a vital role in maintaining resilience to climate change (, , ). They are particularly important for many of the world’s 2.7 billion poor who rely on natural resources most directly for their livelihood and survival. The BirdLife Partnership is contributing to global efforts to conserve and restore ecosystems, which will help mitigate the worst impacts of climate change both locally and globally (, , ). In Africa, modelling studies show that Important Bird Areas (IBAs) are likely to experience high species turnover as a consequence of climate change. It is nevertheless projected that the majority of priority species will retain suitable climate in one or more IBAs where they currently occur. Protecting and expanding the existing network of IBAs will therefore be key to safeguarding both biodiversity and local communities through this period of climatic turmoil ().

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